1. Field of Use
This invention relates generally to adjustable office chairs and, in particular, to improved mechanisms for effecting and controlling backrest reclining motion and for effecting selective adjustment of seat height, seat attitude and backrest attitude.
2. Description of the Prior Art
The prior art discloses numerous versions of adjustable office chairs and adjusting mechanisms therefor. In some office chairs, the seat and backrest are rigidly secured together relative to each other and are mounted on a chair base. The seat and fixed backrest are biased into a standard position by biasing springs but can be tilted backward together to a reclining position on the chair base against spring bias by the chair occupant as he leans back. Typically, no adjustable tilt positioning of the backrest relative to the seat is possible in such a chair. Some prior art chairs employ a valve-controlled pneumatic seat height adjustment mechanism as shown in U.S. Pat. No. 3,711,054 to Bauer, issued Jan. 16, 1973.